Delphi windows 7 control panel component

I just created a small component that looks sort of what you want. It is double-buffered, and hence completely flicker-free, and works both with visual themes enabled and disabled.

unit TaskButton;

interface

uses
  SysUtils, Forms, Messages, Windows, Graphics, Classes, Controls, UxTheme,
  ImgList, PNGImage;

type
  TIconSource = (isImageList, isPNGImage);

  TTaskButtonLinkClickEvent = procedure(Sender: TObject; LinkIndex: integer) of object;

  TTaskButton = class(TCustomControl)
  private
    { Private declarations }
    FCaption: TCaption;
    FHeaderRect: TRect;
    FImageSpacing: integer;
    FLinks: TStrings;
    FHeaderHeight: integer;
    FLinkHeight: integer;
    FLinkSpacing: integer;
    FHeaderSpacing: integer;
    FLinkRects: array of TRect;
    FPrevMouseHoverIndex: integer;
    FMouseHoverIndex: integer;
    FImages: TImageList;
    FImageIndex: TImageIndex;
    FIconSource: TIconSource;
    FImage: TPngImage;
    FBuffer: TBitmap;
    FOnLinkClick: TTaskButtonLinkClickEvent;
    procedure UpdateMetrics;
    procedure SetCaption(const Caption: TCaption);
    procedure SetImageSpacing(ImageSpacing: integer);
    procedure SetLinkSpacing(LinkSpacing: integer);
    procedure SetHeaderSpacing(HeaderSpacing: integer);
    procedure SetLinks(Links: TStrings);
    procedure SetImages(Images: TImageList);
    procedure SetImageIndex(ImageIndex: TImageIndex);
    procedure SetIconSource(IconSource: TIconSource);
    procedure SetImage(Image: TPngImage);
    procedure SwapBuffers;
    function ImageWidth: integer;
    function ImageHeight: integer;
    procedure SetNonThemedHeaderFont;
    procedure SetNonThemedLinkFont(Hovering: boolean = false);
  protected
    { Protected declarations }
    procedure Paint; override;
    procedure WndProc(var Message: TMessage); override;
    procedure MouseDown(Button: TMouseButton; Shift: TShiftState; X: Integer; Y: Integer); override;
    procedure MouseMove(Shift: TShiftState; X: Integer; Y: Integer); override;
    procedure MouseUp(Button: TMouseButton; Shift: TShiftState; X: Integer; Y: Integer); override;
  public
    { Public declarations }
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  published
    { Published declarations }
    property Caption: TCaption read FCaption write SetCaption;
    property Links: TStrings read FLinks write SetLinks;
    property ImageSpacing: integer read FImageSpacing write SetImageSpacing default 16;
    property HeaderSpacing: integer read FHeaderSpacing write SetHeaderSpacing default 2;
    property LinkSpacing: integer read FLinkSpacing write SetLinkSpacing default 2;
    property Images: TImageList read FImages write SetImages;
    property ImageIndex: TImageIndex read FImageIndex write SetImageIndex;
    property Image: TPngImage read FImage write SetImage;
    property IconSource: TIconSource read FIconSource write SetIconSource default isPNGImage;
    property OnLinkClick: TTaskButtonLinkClickEvent read FOnLinkClick write FOnLinkClick;
  end;

procedure Register;

implementation

uses Math;

procedure Register;
begin
  RegisterComponents('Rejbrand 2009', [TTaskButton]);
end;

function IsIntInInterval(x, xmin, xmax: integer): boolean; inline;
begin
  IsIntInInterval := (xmin <= x) and (x <= xmax);
end;

function PointInRect(const Point: TPoint; const Rect: TRect): boolean; inline;
begin
  PointInRect := IsIntInInterval(Point.X, Rect.Left, Rect.Right) and
                 IsIntInInterval(Point.Y, Rect.Top, Rect.Bottom);
end;

{ TTaskButton }

constructor TTaskButton.Create(AOwner: TComponent);
begin
  inherited;
  InitThemeLibrary;
  FBuffer := TBitmap.Create;
  FLinks := TStringList.Create;
  FImage := TPngImage.Create;
  FImageSpacing := 16;
  FHeaderSpacing := 2;
  FLinkSpacing := 2;
  FPrevMouseHoverIndex := -1;
  FMouseHoverIndex := -1;
  FIconSource := isPNGImage;
end;

destructor TTaskButton.Destroy;
begin
  FLinkRects := nil;
  FImage.Free;
  FLinks.Free;
  FBuffer.Free;
  inherited;
end;

function TTaskButton.ImageHeight: integer;
begin

  result := 0;
  case FIconSource of
    isImageList:
      if Assigned(FImages) then
        result := FImages.Height;
    isPNGImage:
      if Assigned(FImage) then
        result := FImage.Height;
  end;

end;

function TTaskButton.ImageWidth: integer;
begin

  result := 0;
  case FIconSource of
    isImageList:
      if Assigned(FImages) then
        result := FImages.Width;
    isPNGImage:
      if Assigned(FImage) then
        result := FImage.Width;
  end;

end;

procedure TTaskButton.MouseDown(Button: TMouseButton; Shift: TShiftState; X,
  Y: Integer);
begin
  inherited;
  Paint;
end;

procedure TTaskButton.MouseMove(Shift: TShiftState; X, Y: Integer);
var
  i: Integer;
begin
  inherited;
  FMouseHoverIndex := -1;
  for i := 0 to high(FLinkRects) do
    if PointInRect(point(X, Y), FLinkRects[i]) then
    begin
      FMouseHoverIndex := i;
      break;
    end;

  if FMouseHoverIndex <> FPrevMouseHoverIndex then
  begin
    Cursor := IfThen(FMouseHoverIndex <> -1, crHandPoint, crDefault);
    Paint;
  end;

  FPrevMouseHoverIndex := FMouseHoverIndex;
end;

procedure TTaskButton.MouseUp(Button: TMouseButton; Shift: TShiftState; X,
  Y: Integer);
begin
  inherited;
  Paint;
  if (FMouseHoverIndex <> -1) and Assigned(FOnLinkClick) then
    FOnLinkClick(Self, FMouseHoverIndex);
end;

procedure TTaskButton.Paint;
var
  theme: HTHEME;
  i: Integer;
  pnt: TPoint;
  r: PRect;
begin
  inherited;

  if FLinks.Count <> length(FLinkRects) then
    UpdateMetrics;

  FBuffer.Canvas.Brush.Color := Color;
  FBuffer.Canvas.FillRect(ClientRect);


  if GetCursorPos(pnt) then
    if PointInRect(Self.ScreenToClient(pnt), ClientRect) then
    begin

      if UxTheme.UseThemes then
      begin

        theme := OpenThemeData(Handle, 'BUTTON');
        if theme <> 0  then
          try
            DrawThemeBackground(theme,
                                FBuffer.Canvas.Handle,
                                BP_COMMANDLINK,
                                CMDLS_HOT,
                                ClientRect,
                                nil);
          finally
            CloseThemeData(theme);
          end;

      end
      else
      begin

        New(r);
        try
          r^ := ClientRect;
          DrawEdge(FBuffer.Canvas.Handle, r^, EDGE_RAISED, BF_RECT);
        finally
          Dispose(r);
        end;

      end;

    end;

  case FIconSource of
    isImageList:
      if Assigned(FImages) then
        FImages.Draw(FBuffer.Canvas, 14, 16, FImageIndex);
    isPNGImage:
      if Assigned(FImage) then
        FBuffer.Canvas.Draw(14, 16, FImage);
  end;

  if UxTheme.UseThemes then
  begin

    theme := OpenThemeData(Handle, 'CONTROLPANEL');

    if theme <> 0 then
      try

        DrawThemeText(theme,
                      FBuffer.Canvas.Handle,
                      CPANEL_SECTIONTITLELINK,
                      CPSTL_NORMAL,
                      PChar(Caption),
                      length(Caption),
                      DT_LEFT or DT_END_ELLIPSIS or DT_TOP or DT_SINGLELINE,
                      0,
                      FHeaderRect);

        for i := 0 to FLinks.Count - 1 do
          DrawThemeText(theme,
                        FBuffer.Canvas.Handle,
                        CPANEL_CONTENTLINK,
                        IfThen(FMouseHoverIndex = i, IfThen(csLButtonDown in ControlState, CPCL_PRESSED, CPCL_HOT), CPCL_NORMAL),
                        PChar(FLinks[i]),
                        length(FLinks[i]),
                        DT_LEFT or DT_END_ELLIPSIS or DT_TOP or DT_SINGLELINE,
                        0,
                        FLinkRects[i]
                       );

      finally
        CloseThemeData(theme);
      end;

  end
  else
  begin

    SetNonThemedHeaderFont;
    DrawText(FBuffer.Canvas.Handle,
             PChar(Caption),
             -1,
             FHeaderRect,
             DT_LEFT or DT_END_ELLIPSIS or DT_TOP or DT_SINGLELINE);

    for i := 0 to FLinks.Count - 1 do
    begin
      SetNonThemedLinkFont(FMouseHoverIndex = i);
      DrawText(FBuffer.Canvas.Handle,
               PChar(FLinks[i]),
               -1,
               FLinkRects[i],
               DT_LEFT or DT_END_ELLIPSIS or DT_TOP or DT_SINGLELINE);
    end;

  end;

  SwapBuffers;
end;

procedure TTaskButton.SetCaption(const Caption: TCaption);
begin
  if not SameStr(FCaption, Caption) then
  begin
    FCaption := Caption;
    UpdateMetrics;
    Paint;
  end;
end;

procedure TTaskButton.SetHeaderSpacing(HeaderSpacing: integer);
begin
  if FHeaderSpacing <> HeaderSpacing then
  begin
    FHeaderSpacing := HeaderSpacing;
    UpdateMetrics;
    Paint;
  end;
end;

procedure TTaskButton.SetIconSource(IconSource: TIconSource);
begin
  if FIconSource <> IconSource then
  begin
    FIconSource := IconSource;
    UpdateMetrics;
    Paint;
  end;
end;

procedure TTaskButton.SetImage(Image: TPngImage);
begin
  FImage.Assign(Image);
  UpdateMetrics;
  Paint;
end;

procedure TTaskButton.SetImageIndex(ImageIndex: TImageIndex);
begin
  if FImageIndex <> ImageIndex then
  begin
    FImageIndex := ImageIndex;
    UpdateMetrics;
    Paint;
  end;
end;

procedure TTaskButton.SetImages(Images: TImageList);
begin
  FImages := Images;
  UpdateMetrics;
  Paint;
end;

procedure TTaskButton.SetImageSpacing(ImageSpacing: integer);
begin
  if FImageSpacing <> ImageSpacing then
  begin
    FImageSpacing := ImageSpacing;
    UpdateMetrics;
    Paint;
  end;
end;

procedure TTaskButton.SetLinks(Links: TStrings);
begin
  FLinks.Assign(Links);
  UpdateMetrics;
  Paint;
end;

procedure TTaskButton.SetLinkSpacing(LinkSpacing: integer);
begin
  if FLinkSpacing <> LinkSpacing then
  begin
    FLinkSpacing := LinkSpacing;
    UpdateMetrics;
    Paint;
  end;
end;

procedure TTaskButton.SwapBuffers;
begin
  BitBlt(Canvas.Handle, 0, 0, Width, Height, FBuffer.Canvas.Handle, 0, 0, SRCCOPY);
end;

procedure TTaskButton.WndProc(var Message: TMessage);
begin
  inherited;
  case Message.Msg of
    WM_SIZE:
      UpdateMetrics;
    CM_MOUSEENTER:
      Paint;
    CM_MOUSELEAVE:
      Paint;
    WM_ERASEBKGND:
      Message.Result := 1;
  end;
end;


procedure TTaskButton.UpdateMetrics;
var
  theme: HTHEME;
  cr, r: TRect;
  i, y: Integer;
begin

  FBuffer.SetSize(Width, Height);
  SetLength(FLinkRects, FLinks.Count);

  if UxTheme.UseThemes then
  begin

    theme := OpenThemeData(Handle, 'CONTROLPANEL');

    if theme <> 0 then
      try

        with cr do
        begin
          Top := 10;
          Left := ImageWidth + FImageSpacing;
          Right := Width - 4;
          Bottom := Self.Height;
        end;

        GetThemeTextExtent(theme,
                           FBuffer.Canvas.Handle,
                           CPANEL_SECTIONTITLELINK,
                           CPSTL_NORMAL,
                           PChar(Caption),
                           -1,
                           DT_LEFT or DT_END_ELLIPSIS or DT_TOP or DT_SINGLELINE,
                           @cr,
                           r);

        FHeaderHeight := r.Bottom - r.Top;

        with FHeaderRect do
        begin
          Top := 10;
          Left := 14 + ImageWidth + FImageSpacing;
          Right := Width - 4;
          Bottom := Top + FHeaderHeight;
        end;

        with cr do
        begin
          Top := 4;
          Left := 14 + ImageWidth + FImageSpacing;
          Right := Width - 4;
          Bottom := Self.Height;
        end;

        y := FHeaderRect.Bottom + FHeaderSpacing;
        for i := 0 to high(FLinkRects) do
        begin

          GetThemeTextExtent(theme,
                             FBuffer.Canvas.Handle,
                             CPANEL_CONTENTLINK,
                             CPCL_NORMAL,
                             PChar(FLinks[i]),
                             -1,
                             DT_LEFT or DT_END_ELLIPSIS or DT_TOP or DT_SINGLELINE,
                             @cr,
                             r);

          FLinkHeight := r.Bottom - r.Top;

          FLinkRects[i].Left := FHeaderRect.Left;
          FLinkRects[i].Top := y;
          FLinkRects[i].Right := FLinkRects[i].Left + r.Right - r.Left;
          FLinkRects[i].Bottom := FLinkRects[i].Top + FLinkHeight + FLinkSpacing;

          inc(y, FLinkHeight + FLinkSpacing);
        end;

      finally
        CloseThemeData(theme);
      end;
  end
  else
  begin

    SetNonThemedHeaderFont;

    FHeaderHeight := FBuffer.Canvas.TextHeight(FCaption);

    with FHeaderRect do
    begin
      Top := 10;
      Left := 14 + ImageWidth + FImageSpacing;
      Right := Width - 4;
      Bottom := Top + FHeaderHeight;
    end;

    SetNonThemedLinkFont;

    y := FHeaderRect.Bottom + FHeaderSpacing;
    for i := 0 to high(FLinkRects) do
      with FBuffer.Canvas.TextExtent(FLinks[i]) do
      begin

        FLinkHeight := cy;

        FLinkRects[i].Left := FHeaderRect.Left;
        FLinkRects[i].Top := y;
        FLinkRects[i].Right := FLinkRects[i].Left + cx;
        FLinkRects[i].Bottom := FLinkRects[i].Top + FLinkHeight + FLinkSpacing;

        inc(y, FLinkHeight + FLinkSpacing);
      end;

  end;

end;

procedure TTaskButton.SetNonThemedHeaderFont;
begin
  with FBuffer.Canvas.Font do
  begin
    Color := clNavy;
    Style := [];
    Size := 14;
  end;
end;

procedure TTaskButton.SetNonThemedLinkFont(Hovering: boolean = false);
begin
  with FBuffer.Canvas.Font do
  begin
    Color := clNavy;
    if Hovering then
      Style := [fsUnderline]
    else
      Style := [];
    Size := 10;
  end;
end;

initialization
  // Override Delphi's ugly hand cursor with the nice Windows hand cursor
  Screen.Cursors[crHandPoint] := LoadCursor(0, IDC_HAND);


end.

Screenshots:

If I get time over I will add a keyboard interface to it.